It is known in principle in computed tomography to apply contrast medium in order to amplify an image contrast, in particular when representing vessel structures, and thereby to produce an improved image contrast such that the tissue structures or vessel structures that are of interest can be displayed pictorially with a higher contrast. As a rule, use is made here mostly of iodine-containing, liquid, chemical compounds that are not without problems with reference to their biological compatibility. As a rule, after such an application of contrast media, the liver values are still raised in the patients thus examined months after the application.